It is important to get a feel for which Materials are needed for which projects. Iron and Uranium are the most common and most used Materials, due to their use in construction and energy production, respectively. Magnesium is highly valued for its ability to make things go boom, and so is used in weapons, both explosive and projectile. Gold is used for circuitry; Silicon for chips and thick glass; and Platinum, Silver, Nickel, and Cobalt for various specialized uses. Gravel is itself very common (coming from the omnipresent Stone), but is only a crafting ingredient in Reactor Components and can otherwise be ignored or trashed.